Q-BRIDGE: Computer-aided structural assessment of concrete bridge decks under traffic loads

Engineering practice and guidelines for existing bridges frequently require simplified structural assessment methods to support decision-making by facility managers. This paper presents Q-BRIDGE, a novel computer-aided assessment tool with graphical user interface for rapid safety checks and fragility analysis of both reinforced concrete and prestressed concrete bridge decks under alternative traffic load models according to either Eurocode or Italian guidelines for existing roadway bridges. The background methodology integrates simplified structural analysis, Eurocode-conforming capacity models, uncertainty modelling and performance assessment within a unified computational framework. Multi-level fragility analyses can be performed by considering uncertainties in gravity loads, material properties, geometric properties, and Eurocode-conforming capacity models. User-defined random variables and correlation models are assigned to geometric and material properties, which can be modified to account for deterioration effects. Q-BRIDGE also enables deterministic code-based safety checks under a prescribed traffic load pattern. The software is validated against experimental results obtained from a proof load test on an existing bridge deck, showing satisfactory agreement between predicted and measured structural response. Finally, Q-BRIDGE is applied to a real bridge representative of Italian PC bridges, demonstrating its potential for risk-informed bridge classification and prioritisation of inspections, monitoring, detailed structural assessments and retrofit interventions.